The present invention relates to improvements in a burglar alarm system mounted in a reinforced doorway framing for preventing forcible entry into a structure closed by a door, such as fully disclosed and claimed in my U.S. Pat. No. 4,074,484, dated Feb. 21, 1978, whose disclosure is incorporated herein by way of reference.
The doorway framing disclosed in my patent comprises a wooden door jamb having two substantially parallel major faces and two minor faces substantially perpendicular to the major faces, one of the major faces having a recessed end portion delimited by one of the minor faces and a shoulder constituting a stop for a door, and the door jamb defining a door latch bolt hole in the recessed end portion. The door jamb is mounted on a wall including wooden wall stud means adjacent the other major face of the door jamb, the other major face and the wall defining a narrow space therebetween. A reinforcement metal plate extends over a substantial portion of the wall stud means and a substantial portion of the one minor face of the door jamb, the reinforcement plate being securely affixed to the wall stud means and the one minor door jamb face and covering a substantial region of the minor door jamb face adjacent and beyond the door latch bolt hole, the securely affixed plate holding the door jamb firmly in position. A striker plate defines a hole registering with the bolt hole and is mounted thereover on the jamb.
In my copending U.S. patent application Ser. No. 888,412, filed Mar. 20, 1978, I have disclosed an improvement in such a doorway framing, which comprises an electrically conductive rigid backer plate arranged in the narrow space in contact with the other major face of the door jamb and in registry with the striker plate, and fastening elements securing the striker and backer plates to the door jamb, the fastening elements passing through the door jamb between the striker and backer plates whereby the door jamb is sandwiched between the striker and backer plates. The disclosure of this application is also incorporated herein by way of reference.
In my U.S. Pat. No. 4,178,588, dated Dec. 11, 1979, I have disclosed and claimed a burglar alarm system having an electrical control circuit connected to a reinforced doorway framing of the above-described type for setting off a burglar alarm.